LAUSR

Previously, we demonstrated that the phytoecdysteroid, 20-hydroxyecdysone (20E), accelerates the recovery of skeletal muscle function 7 days following eccentric contraction-induced injury. We hypothesized that 20E may influence the inflammatory response during recovery from eccentric muscle injury; therefore, male mice (3-6 mo) were subjected to eccentric damage of the anterior crural muscles via 150 eccentric contractions, then treated with either 20E (50mg/kg body mass) or vehicle daily until sacrifice (12 hours, 2 days or 4 days post-injury). Using immunohistochemical techniques, infiltration of neutrophils, M1-like, and M2-like macrophages were examined in sectioned tibialis anterior muscle. Our findings revealed that pro-inflammatory responses (infiltration of neutrophils and M1-like macrophages) appear to be attenuated in 20E-treated mice at 12 hours and 2 days post-injury, respectively; whereas anti-inflammatory responses (infiltration of M2-like macrophages) appeared to increase with 20E treatment at 4 days after eccentric muscle injury. Taken together, it is possible that 20E may attenuate the overall early pro-inflammatory response, while bolstering the later anti-inflammatory response to eccentric muscle injury, leading to accelerated muscle repair/regeneration. This research was partly funded by the Appalachian State University Office of Student Research. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.